Section 2 Covalent Bonding

Covalent Bonds Covalent bonds form  When atoms share electrons to complete octets.  Between two nonmetal atoms.  Between nonmetal atoms from Groups 4A(14), 5A(15), 6A(16), and 7A(17).

Hydrogen Molecule (H 2 ) In a hydrogen molecule (H 2 ), each H atom  Shares electrons to form a covalent single bond.  Acquires two (2) electrons.  Becomes stable like helium (He).

Forming Octets in Molecules In a fluorine F 2 molecule, each F atom  Shares one electron.  Acquires an octet.

Diatomic Elements  These elements share electrons to form diatomic, covalent molecules.

Learning Check What is the name of each of the following diatomic molecules? H 2______________________ N 2 _______________ Cl 2 _______________ O 2 _______________ I 2 _______________

Carbon forms 4 covalent bonds In a CH 4, methane, molecule  The central C atom shares 4 electrons to attain an octet.  Each H atom shares 1 electron with the carbon atom to become stable like He.

Electron-Dot Formula for NH 3  In NH 3, a N atom is bonded to three H atoms.   N  and 3 H    The electron dot structure is written as: H Bonding pairs H   │ H : N : H or H─N─N     lone pair of electrons

Electron-Dot Formulas and Models of Some Covalent Compounds

Single and Multiple Bonds In a single bond  One pair of electrons is shared. In a double bond,  Two pairs of electrons are shared. In a triple bond.  Three pairs of electrons are shared.

Electron-Dot Formula of CS 2 Write the electron-dot formula for CS 2. STEP 1 Determine the atom arrangement. The C atom is the central atom. S C S STEP 2 Determine the total number of valence electrons for 1C and 2S. 1C(4e - ) + 2S(6e - ) = 16e -

Electron-Dot Formula of CS 2 STEP 3 Attach each S atom to the central C atom using one electron pair. S : C : S 16e e - = 12e - left STEP 4 Attach 12 remaining electrons as 6 lone pairs to complete octets..... : S : C : S :....

Electron-Dot Formula of CS 2 STEP 5 To complete octets, form one or more multiple bonds. Convert two lone pairs to bonding pairs between C and S atoms to make two double bonds : S : : C : : S : or : S = C = S :

A Nitrogen Molecule has A Triple Bond In a nitrogen molecule, N 2,  Each N atom shares 3 electrons.  Each N atom attains an octet.  The sharing of 3 sets of electrons is a multiple bond called a triple bond.

Covalent Compounds Weak forces between molecules, not the strong covalent bonds within each molecule, are responsible for the physical properties of covalent compounds. Covalent compounds have relatively low melting and boiling points. Most covalent compounds are poor electrical conductors. Strong forces within molecules, weak forces between them

Strong covalent bonding forces within molecules Weak intermolecular forces between molecules

Polar Covalent Polar covalent is a description of a bond that has an uneven distribution of charge due to an unequal sharing of bonding electrons. The boy is not equally sharing with anyone else but rather taking all the food for himself

Polar Covalent

Non-Polar Covalent Non polar covalent is a covalent bond that has an even distribution of charge due to an equal sharing of bonding electrons. This couple is non- polar because they are sharing the drink equally between them.

Non-Polar Covalent

Just as a summary to what each bond looks like…